Traffic controlling system



Feb; 20, 1934. H J, Ll L ELD 1,948,424

TRAFFIC CONTROLLING SYSTEM Filed April 1, 1950 2 Sheets-Sheet l A 'ITORNE V 1934- H. J. LITTLEFIELD 1 1,948,424

TRAFFIC CONTROLLING SYSTEM Filed April 1, 1950 2 Sheets-Sheet 2 V IIIIIIIIIIIIIIIIA INVENTOI? 7 A TTURNE Y Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE 3 Claims.

The present invention relates to visible signal street trafiic-controlling systems having a neutral, warning or pedestrian period between the end of the stop period and the beginning of the go period, and conversely between the ending of the go period and the beginning of the stop period, the purpose of this neutral period being to allow a brief time for the change of flow of traffic and to enable pedestrians already crossing the street to reach the sidewalk before the traffic is again set in motion.

Several types of such systems are known employing either lights or semaphore arms as the visible signal. One type employs a single lens before which are alternately placed red and green shutters, a dark interval between the red and green lights constituting the neutral period, another type employs two separate lights, one red and the other green with a dark interval between them for the neutral period, another type is similar to the last but affords a four-way red indication for the neutral period, while yet a further type employs three lights, red, green and amber, the amber light constituting the neutral period. This latter type may be operated in three different ways, the first being what is known as the amber overlap Working in the sequence, green, green and amber, red, red and amber, green, etc. the second being what is known as the non-overlap working in the sequence, green, amber, red, amber, green,

'etc.; and the third being what is known as the green amber overlap or split-amber (synonymous terms) working in the sequence, green, green and amber, red, green, etc., that is the amber overlaps the green but not the red. The present invention is applicable to any of the aforesaid types of traffic controlling systems or to any system which is to have the beginning and end of a neutral period announced by audible signals automatically timed in relation to visible signals.

An object of the present invention is to provide in conjunction with a traffic controlling system affording a neutral period means for automatically giving audible signals at the beginning and the end of the neutral period in synchronization with the visible signals controlling the period.

A further object is to provide automatic coded police whistle signals at the beginning and end of the neutral period, e. g. a long police whistle blast at the beginning of the period and two short blasts at the end thereof.

A further object is to provide means for varying the interval between the beginning and end ing audible signals for the neutral period.

Yet another object is to provide an independent self-contained unit which may readily be fitted to any existing neutral period traffic-controlling system for the purpose of giving coded or other audible signals at the beginning and end of the neutral period.

Referring to the drawings:

Fig. 1 is a diagrammatic view of the invention as applied to a four-way, three-section, system operating on the split-amber principle. As such a system operating in this manner is well known, only sufiicient of the wiring of the system has been shown to illustrate the pick-up from the amber circuit thereof to the present invention.

Fig. 2 is a diagrammatic cross-section through the motor operating the audible signals, showing 7 the contact disc, reducing gear, and code-wheels upon the motor shaft.

Fig. 3 is a side View of the contact wheel.

Fig. 4 is a side view of the code wheels, one behind the other.

Fig. 5 is a diagrammatic sketch of the relay and the connections leading thereto from the traffic system and from the relay to the remainder of the unit.

' Referring to the drawings, at the left-hand side of Fig. 1 are shown the red, green and amber lights of a four-way green-amber overlap or splitamber trafficcontrolling system, the upper lamps l, 2 and 3 being for the main street and the lower lamps 4, 5 and 6 for the cross street. As the wiring and other apparatus for operating the lights of such a system are well known, only sufficient thereof is shown as is necessary to illustrate the present invention. As will be seen, all the lights, I both upper and lower, operate with a common return wire 7, while the upper red light 1 and the lower green light 6 have a common feed wire 8 and the upper green light 3 and the lower red light 4 have a common feed wire 9. The upper and lower amber lights 2, 5 are in separate circuits, g5 fed, respectively, by lead-in wires 10 and 11, both of which are energized through the medium of the contact 12 according to whether it is moved to the left or right in a manner well known in the operation of the lights of the controlling system.

All the foregoing relates to apparatus well known in the prior art and I will now describe the present invention as applied thereto, which broadly comprises means for giving automatic audible signals at the beginning and end of the neutral period which are in synchronism with the visible signals governing this period. For this purpose I provide a synchrono us or variable type, small, single phase motor A, a two-stage volume air-blower and motor E, and an electromagnetioally operated air valve F, which controls a standard type police traflic whistle G. The shaft S of motor A drives, through a variable gear reduction unit R, a shaft S on which are mounted for rotation therewith three discs A B and B The disc A has a notch 13 in its periphery, while the disc B has a long cam projection 14, and the disc B two short cam projections 15, 16, all for a purpose to be hereinafter explained. The wires L L are the lead-in and lead-out wires, respectively, for the current which operates the motor A, blower-motor E and the electro-magnetical'ly operated valve F. This current supply is controlled by a sensitive, balanced relay C, specially designed to operate on a current of very low value, which is less than that required to operate the amber lights of the controlling system. This low value current for operating the relay is obtained from the lighted amber light circuit by one or other of the wires 17, 18, as the case may be. The relay C has a single-pole double-throw contact C', C and two pairs of stationary contacts C C and C C which are provided so that the device may be operated irrespective of whether the occurrence of the neutral period of the controlling system is brought about by the opening or the closing of a circuit. If the former is the case, the leads Y Y are connected to relay contacts C --C as clearly shown by the dotted lines (2 and d in Fig. 5, while if the latter is the case as in the embodiment of the invention herein described and illustrated-they are connected to relay contacts C ---C as clearly shown by the solid lines D and D in Fig. 5.

The operation of the invention is as follows: Let us assume that in the operation of the visible signals of the controlling system the top green and bottom red lights are lighted by current supplied through the lead 9. The next step in the cycle of operation of the visible signals would be the appearing of the amber light 2 upon the main street, which overlaps the green light 3, thus inaugurating the neutral or pedestrian period. This amber light upon the main street is lighted by the contact 12 being moved to the right to engage the lead 10. Immediately this takes place, current is shunted from the lead 10 by means of the lead 17 through the relay C, and back through the lead 18 to the return lead 7 of the lighted amber circuit. It will be noticed that in passing back to the lead '7 the shunted current passes through the dead amber lamp or lamps 5 of the cross-street, which lamp or lamps are, therefore, used as a resistance in series with the relay C; and as the relay is designed to operate upon much less current than that required by the lamp, the relay operates without lighting the off amber lamp, which in the case under discussion is the lamp 5.

Immediately the relay 0 is energized the armature thereof bridges the contacts C C thus closing the circuit:lead L lead 19, terminal E motor of blower E, terminal E leads 20, Y relay, contacts 0 C leads Y to return wire L thus starting up the motor of the volume blower E. Simultaneously the circuit:leads L and 23, terminal A motor A, terminal A leads 22, 21, Y relay contacts C C lead Y to return lead L is completed, thus starting up the motor A. As soon as the motor starts it revolves the contact disc A which lifts the contact A normally resting in the notch 13, into engagement with the contact A thus maintaining circuits through the motor A and the motor of the blower-motor E l for a complete revolution of the disc A no matter whether the relay C is energized or not. The reason for this will be explained later.

As the discs B B are rigidly secured upon the same shaft as the disc A they will rotate therewith. Thus, as soon as the motor A starts up, the cam 14 upon the disc B lifts contact B into engagement with contact B and completes the circuit:leads L 23, 26, terminal F coils of electromagnetically operated valve F, terminal F lead 25, contacts B B to return lead L with the result that a long blast upon the whistle G is produced. The length of this blast depends upon the peripheral length of the cam 14, and as soon as this cam passes the contact B the latter drops back and breaks the circuit and so silences the whistle. The discs B and B continue to revolve until the cam 16 on disc B engages contact B and again completes the circuit to cause a short blast upon the whistle governed in duration by the peripheral length of the contact 16. Similarly, continued rotation of the discs B and B causes the cam 15 to efiect another short blast upon the whistle. The time interval between the beginning of the first blast and the end of the last blast depends, of course, upon the speed of rotation of the discs B and B and the peripheral distance between the forward end of the cam 14 and the rear end of the cam 15. As it is the object of the present invention to provide means for emitting an audible signal at the beginning and end of the neutral period determined by the visible signals, it will be obvious that the aforesaid factors governing the time interval between the audible signals will be arranged so as to make said time interval agree with the length of the neutral period fixed by the visible signals. Should the duration of the neutral period, as governed by the visible signals, be altered, the time interval of the audible signals may readily be changed to agree therewith by adjusting the discs B B relatively to each other. For this purpose the discs B and B are so mounted on the shaft S as to enable them to be shifted by turning them relatively to each other and to the shaft, the discs being then clamped in the desired relation by a nut S In the normal position of the apparatus the forward end of the cam 14 rests against the contact B ready to lift the same as soon as the motor A starts up.

From the foregoing description it is clearly evident that upon the closing of either of the amber circuits thus lighting the amber lights therein and initiating the neutral period, the police whistle G simultaneously emits a long blast, and that upon opening of the said amber circuit and so ending the neutral period the whistle will simultaneously emit two short blasts. This gives a definite audible warning in conjunction with the visible signals, and where an automobilist is not law-minded enough to respect the visible signal he is forcibly reminded by the audible signal, and it is believed that fewer autoists will attempt to beat out the amber light or neutral period, which practice isthe cause of many accidents to both automobilists and pedestrians. Further, as thev audible signals are in synchronism with the visible signals, no lost time will be incurred.

From the above description it will be seen that the cam 15 passes the contact B at the moment the amber light circuit is opened, with the resultant. de-energizing of the relay 0 andthe consequent stoppage of thefeed from L through the relay to the motor A. It is the function of the contact disc A therefore, to maintain a circuit through the motor A until the motor has brought the apparatus to its normal position with the forward end of the cam 14 resting against the contact B at which instant the contact A drops into the notch 13 of disc A thus de-energizing the motor A and bringing the apparatus to rest.

The invention may be constructed as an integral part of traffic-controlling systems, or it may be constructed as a separate complete unit adapted to be fitted to trafiic-controlling systems already in use. Its applicability to any of a large number of types of systems is one of the distinguishing features of the invention.

From the foregoing description it will be evident that the terms synchronous, synchronization and the like are not used in a strictly limited sense, since while the operation of the audible signals is predetermined so as to recur in a definite though variable manner in the cycle of operation of the combined system, the sounding of the audible signals is not necessarily coincident with the changes in the visible signals.

The invention has been illustrated in connection with a split-amber traffic signal, and it has been thought unnecessary to illustrate other types of visible signals, or to illustrate the wiring of a complete system including transmitter timers, receiver timers and the like. There are numerous types of controls for timing or operating traffic signals, such as the induction timer, the synchronous motor timer, the impulse timer, and the traffic operated control, each of these, in turn, embracing numerous forms and modifications. The existence of a suitable control is to be understood in connection with the drawings, also the duplication of the visible signals, and of the associated audible signal unit of this invention, at the various intersections which may be subject to the general system. My invention is independent of the particular mode of operation of the system with which it is used, considered as a whole, since as previously stated in any visible signal system which provides for a neutral period one of two things must take place, namely either an electrical circuit is closed or an elec trical circuit is opened, and all that is necessary is to make the pick-up connections 17, 18 to connect the audible signal unit,

I claim:

1. In a traffic-controlling system having neutral period lights in two-directions, an audible signal device, electrical means for automatically causing said device to emit audible signals at the beginning and end of the aforesaid neutral period, a relay and means through which said relay controls said electrical means, said relay being designed to operate upon a current less than that required to give visibility to the neutral period lights, and a circuit for said relay fed from that of the lighted neutral period lights and including the dead neutral period lights in series resistance with the relay.

2. In a traific controlling system, the combination with a set of traffic lights and electrical means for operating the same for the control of trarfic and including a neutral period, of a traffic whistle, a blower connected with said whistle, a motor for driving said blower, an electromagnetic valve operable for controlling the sounding of said whistle by the blower, a code wheel for controlling said electromagnetic valve to sound the whistle according to a predetermined sequence within said neutral period, a motor for rotating said code wheel, a circuit for energizing said motors and said electromagnetic valve, means interconnected with the means for operating the traiiic lights for initially completing circuits through said motors during the neutral period, locking circuits for said motors, and means for maintaining said locking circuits for a predetermined movement of said code wheel.

3. In a traific controlling system, the combination with a set of traffic lights and electrical means for operating the same for the control of trailic and including a neutral period, of a traffic whistle, means for supplying said whistle with aeriform fluid to sound the same, an electromagnetic valve operable for controlling the sounding of said whistle by the said acriform fluid, a code wheel for operating said electromagnetic valve to sound the whistle according to a predetermined sequence within said neutral period, a motor for rotating said code wheel, a circuit for energizing said motor and said electromagnetic valve, means interconnected with the means for operating the traflic lights for initially compl ting a circuit through said motor during the neutral period, a locking circuit for said motor, and means for maintaining said looking circuit for a predetermined movement of said code wheel.

HARRY J. LITTLEFIELD. 

